package com.po.view.beans.util;



import java.util.Iterator;
import java.util.Locale;
import java.util.Map;
import java.util.MissingResourceException;
import java.util.ResourceBundle;

import javax.el.ELContext;
import javax.el.ExpressionFactory;
import javax.el.MethodExpression;
import javax.el.ValueExpression;

import javax.faces.application.Application;
import javax.faces.application.FacesMessage;
import javax.faces.component.UIComponent;
import javax.faces.component.UIViewRoot;
import javax.faces.context.ExternalContext;
import javax.faces.context.FacesContext;

import javax.servlet.http.HttpServletRequest;


/**
 * General useful static utilies for working with JSF.
 * NOTE: Updated to use JSF 1.2 ExpressionFactory.
 *
 * @author Duncan Mills
 * @author Steve Muench
 * @author Ric Smith
 *
 * $Id: JSFUtils.java 2383 2007-09-17 16:25:37Z drmills $
 */
public class JSFUtil {

  private static final String NO_RESOURCE_FOUND = "Missing resource: ";

  /**
   * Method for taking a reference to a JSF binding expression and returning
   * the matching object (or creating it).
   * @param expression EL expression
   * @return Managed object
   */
  public static Object resolveExpression(String expression) {
    FacesContext facesContext = getFacesContext();
    Application app = facesContext.getApplication();
    ExpressionFactory elFactory = app.getExpressionFactory();
    ELContext elContext = facesContext.getELContext();
    ValueExpression valueExp =
      elFactory.createValueExpression(elContext, expression, Object.class);
    return valueExp.getValue(elContext);
  }

  public static String resolveRemoteUser() {
    FacesContext facesContext = getFacesContext();
    ExternalContext ectx = facesContext.getExternalContext();
    return ectx.getRemoteUser();
  }

  public static String resolveUserPrincipal() {
    FacesContext facesContext = getFacesContext();
    ExternalContext ectx = facesContext.getExternalContext();
    HttpServletRequest request = (HttpServletRequest)ectx.getRequest();
    return request.getUserPrincipal().getName();
  }

  public static Object resloveMethodExpression(String expression,
                                               Class returnType,
                                               Class[] argTypes,
                                               Object[] argValues) {
    FacesContext facesContext = getFacesContext();
    Application app = facesContext.getApplication();
    ExpressionFactory elFactory = app.getExpressionFactory();
    ELContext elContext = facesContext.getELContext();
    MethodExpression methodExpression =
      elFactory.createMethodExpression(elContext, expression, returnType,
                                       argTypes);
    return methodExpression.invoke(elContext, argValues);
  }
  
    public static UIComponent findComponent(String id)
      {
        return findComponent(getFacesContext().getViewRoot(), id);
      }

  /**
   * Method for taking a reference to a JSF binding expression and returning
   * the matching Boolean.
   * @param expression EL expression
   * @return Managed object
   */
  public static Boolean resolveExpressionAsBoolean(String expression) {
    return (Boolean)resolveExpression(expression);
  }

  /**
   * Method for taking a reference to a JSF binding expression and returning
   * the matching String (or creating it).
   * @param expression EL expression
   * @return Managed object
   */
  public static String resolveExpressionAsString(String expression) {
    return (String)resolveExpression(expression);
  }

  /**
   * Convenience method for resolving a reference to a managed bean by name
   * rather than by expression.
   * @param beanName name of managed bean
   * @return Managed object
   */
  public static Object getManagedBeanValue(String beanName) {
    StringBuffer buff = new StringBuffer("#{");
    buff.append(beanName);
    buff.append("}");
    return resolveExpression(buff.toString());
  }

  /**
   * Method for setting a new object into a JSF managed bean
   * Note: will fail silently if the supplied object does
   * not match the type of the managed bean.
   * @param expression EL expression
   * @param newValue new value to set
   */
  public static void setExpressionValue(String expression, Object newValue) {
    FacesContext facesContext = getFacesContext();
    Application app = facesContext.getApplication();
    ExpressionFactory elFactory = app.getExpressionFactory();
    ELContext elContext = facesContext.getELContext();
    ValueExpression valueExp =
      elFactory.createValueExpression(elContext, expression, Object.class);

    //Check that the input newValue can be cast to the property type
    //expected by the managed bean.
    //If the managed Bean expects a primitive we rely on Auto-Unboxing
    //I could do a more comprehensive check and conversion from the object
    //to the equivilent primitive but life is too short
    Class bindClass = valueExp.getType(elContext);
    if (bindClass.isPrimitive() || bindClass.isInstance(newValue)) {
      valueExp.setValue(elContext, newValue);
    }
  }

  /**
   * Convenience method for setting the value of a managed bean by name
   * rather than by expression.
   * @param beanName name of managed bean
   * @param newValue new value to set
   */
  public static void setManagedBeanValue(String beanName, Object newValue) {
    StringBuffer buff = new StringBuffer("#{");
    buff.append(beanName);
    buff.append("}");
    setExpressionValue(buff.toString(), newValue);
  }


  /**
   * Convenience method for setting Session variables.
   * @param key object key
   * @param object value to store
   */

  public static void storeOnSession(String key, Object object) {
    FacesContext ctx = getFacesContext();
    Map sessionState = ctx.getExternalContext().getSessionMap();
    sessionState.put(key, object);
  }

  /**
   * Convenience method for getting Session variables.
   * @param key object key
   * @return session object for key
   */
  public static Object getFromSession(String key) {
    FacesContext ctx = getFacesContext();
    Map sessionState = ctx.getExternalContext().getSessionMap();
    return sessionState.get(key);
  }

  public static String getFromHeader(String key) {
    FacesContext ctx = getFacesContext();
    ExternalContext ectx = ctx.getExternalContext();
    return ectx.getRequestHeaderMap().get(key);
  }

  /**
   * Convenience method for getting Request variables.
   * @param key object key
   * @return session object for key
   */
  public static Object getFromRequest(String key) {
    FacesContext ctx = getFacesContext();
    Map sessionState = ctx.getExternalContext().getRequestMap();
    return sessionState.get(key);
  }

  /**
   * Pulls a String resource from the property bundle that
   * is defined under the application &lt;message-bundle&gt; element in
   * the faces config. Respects Locale
   * @param key string message key
   * @return Resource value or placeholder error String
   */
  public static String getStringFromBundle(String key) {
    ResourceBundle bundle = getBundle();
    return getStringSafely(bundle, key, null);
  }


  /**
   * Convenience method to construct a <code>FacesMesssage</code>
   * from a defined error key and severity
   * This assumes that the error keys follow the convention of
   * using <b>_detail</b> for the detailed part of the
   * message, otherwise the main message is returned for the
   * detail as well.
   * @param key for the error message in the resource bundle
   * @param severity severity of message
   * @return Faces Message object
   */
  public static FacesMessage getMessageFromBundle(String key,
                                                  FacesMessage.Severity severity) {
    ResourceBundle bundle = getBundle();
    String summary = getStringSafely(bundle, key, null);
    String detail = getStringSafely(bundle, key + "_detail", summary);
    FacesMessage message = new FacesMessage(summary, detail);
    message.setSeverity(severity);
    return message;
  }

  /**
   * Add JSF info message.
   * @param msg info message string
   */
  public static void addFacesInformationMessage(String msg) {
    FacesContext ctx = getFacesContext();
    FacesMessage fm = new FacesMessage(FacesMessage.SEVERITY_INFO, msg, "");
    ctx.addMessage(getRootViewComponentId(), fm);
  }

  /**
   * Add JSF error message.
   * @param msg error message string
   */
  public static void addFacesErrorMessage(String msg) {
    FacesContext ctx = getFacesContext();
    FacesMessage fm = new FacesMessage(FacesMessage.SEVERITY_ERROR, msg, "");
    ctx.addMessage(getRootViewComponentId(), fm);
  }

  /**
   * Add JSF error message for a specific attribute.
   * @param attrName name of attribute
   * @param msg error message string
   */
  public static void addFacesErrorMessage(String attrName, String msg) {
    // TODO: Need a way to associate attribute specific messages
    //       with the UIComponent's Id! For now, just using the view id.
    //TODO: make this use the internal getMessageFromBundle?
    FacesContext ctx = getFacesContext();
    FacesMessage fm =
      new FacesMessage(FacesMessage.SEVERITY_ERROR, attrName, msg);
    ctx.addMessage(getRootViewComponentId(), fm);
  }

  // Informational getters

  /**
   * Get view id of the view root.
   * @return view id of the view root
   */
  public static String getRootViewId() {
    return getFacesContext().getViewRoot().getViewId();
  }

  /**
   * Get component id of the view root.
   * @return component id of the view root
   */
  public static String getRootViewComponentId() {
    return getFacesContext().getViewRoot().getId();
  }

  /**
   * Get FacesContext.
   * @return FacesContext
   */
  public static FacesContext getFacesContext() {
    return FacesContext.getCurrentInstance();
  }
  /*
   * Internal method to pull out the correct local
   * message bundle
   */

  private static ResourceBundle getBundle() {
    FacesContext ctx = getFacesContext();
    UIViewRoot uiRoot = ctx.getViewRoot();
    Locale locale = uiRoot.getLocale();
    ClassLoader ldr = Thread.currentThread().getContextClassLoader();
    return ResourceBundle.getBundle(ctx.getApplication().getMessageBundle(),
                                    locale, ldr);
  }

  /**
   * Get an HTTP Request attribute.
   * @param name attribute name
   * @return attribute value
   */
  public static Object getRequestAttribute(String name) {
    return getFacesContext().getExternalContext().getRequestMap().get(name);
  }

  /**
   * Set an HTTP Request attribute.
   * @param name attribute name
   * @param value attribute value
   */
  public static void setRequestAttribute(String name, Object value) {
    getFacesContext().getExternalContext().getRequestMap().put(name, value);
  }

  /*
   * Internal method to proxy for resource keys that don't exist
   */

  private static String getStringSafely(ResourceBundle bundle, String key,
                                        String defaultValue) {
    String resource = null;
    try {
      resource = bundle.getString(key);
    } catch (MissingResourceException mrex) {
      if (defaultValue != null) {
        resource = defaultValue;
      } else {
        resource = NO_RESOURCE_FOUND + key;
      }
    }
    return resource;
  }

  /**
   * Locate an UIComponent in view root with its component id. Use a recursive way to achieve this.
   * Taken from http://www.jroller.com/page/mert?entry=how_to_find_a_uicomponent
   * @param id UIComponent id
   * @return UIComponent object
   */
  public static UIComponent findComponentInRoot(String id) {
    UIComponent component = null;
    FacesContext facesContext = FacesContext.getCurrentInstance();
    if (facesContext != null) {
      UIComponent root = facesContext.getViewRoot();
      component = findComponent(root, id);
    }
    return component;
  }

  /**
   * Locate an UIComponent from its root component.
   * Taken from http://www.jroller.com/page/mert?entry=how_to_find_a_uicomponent
   * @param base root Component (parent)
   * @param id UIComponent id
   * @return UIComponent object
   */
  public static UIComponent findComponent(UIComponent base, String id) {
    if (id.equals(base.getId()))
      return base;

    UIComponent children = null;
    UIComponent result = null;
    Iterator childrens = base.getFacetsAndChildren();
    while (childrens.hasNext() && (result == null)) {
      children = (UIComponent)childrens.next();
      if (id.equals(children.getId())) {
        result = children;
        break;
      }
      result = findComponent(children, id);
      if (result != null) {
        break;
      }
    }
    return result;
  }

  /**
   * Method to create a redirect URL. The assumption is that the JSF servlet mapping is
   * "faces", which is the default
   *
   * @param view the JSP or JSPX page to redirect to
   * @return a URL to redirect to
   */
  public static String getPageURL(String view) {
    FacesContext facesContext = getFacesContext();
    ExternalContext externalContext = facesContext.getExternalContext();
    String url =
      ((HttpServletRequest)externalContext.getRequest()).getRequestURL().toString();
    StringBuffer newUrlBuffer = new StringBuffer();
    newUrlBuffer.append(url.substring(0, url.lastIndexOf("faces/")));
    newUrlBuffer.append("faces");
    String targetPageUrl = view.startsWith("/") ? view : "/" + view;
    newUrlBuffer.append(targetPageUrl);
    return newUrlBuffer.toString();
  }

  public static Object invokeMethodExpression(String expr, Class returnType,
                                              Class[] argTypes,
                                              Object[] args) {
    FacesContext fc = FacesContext.getCurrentInstance();
    ELContext elctx = fc.getELContext();
    ExpressionFactory elFactory = fc.getApplication().getExpressionFactory();
    MethodExpression methodExpr =
      elFactory.createMethodExpression(elctx, expr, returnType, argTypes);
    return methodExpr.invoke(elctx, args);
  }

  public static Object invokeMethodExpression(String expr, Class returnType,
                                              Class argType, Object argument) {
    return invokeMethodExpression(expr, returnType, new Class[] { argType },
                                  new Object[] { argument });
  }
}


